# 启动文件扫描任务

## 场景介绍

Enterprise Data Guard Kit为应用提供公共路径和指定目录的扫描能力，获取对应目录下的文件列表。

## 接口说明

详细接口说明可参考[接口文档](https://developer.huawei.com/consumer/cn/doc/harmonyos-references/dataguard-fileguard)。

|接口名|描述|
|:------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|:-------------------------|
|[startFileScanTask](https://developer.huawei.com/consumer/cn/doc/harmonyos-references/dataguard-fileguard#startfilescantask)(type: [CommonDirScanType](https://developer.huawei.com/consumer/cn/doc/harmonyos-references/dataguard-fileguard#commondirscantype), callback: [ScanFileCallback](https://developer.huawei.com/consumer/cn/doc/harmonyos-references/dataguard-fileguard#scanfilecallback), batchNum?: number): void|通过Callback的方式，扫描公共目录并返回结果。|
|[startFileScanTask](https://developer.huawei.com/consumer/cn/doc/harmonyos-references/dataguard-fileguard#startfilescantask-1)(path: string, callback: [ScanFileCallback](https://developer.huawei.com/consumer/cn/doc/harmonyos-references/dataguard-fileguard#scanfilecallback), batchNum?: number): void|通过Callback的方式，扫描指定目录并返回结果。|

## 开发步骤

1. 导入模块。

   ```typescript
   import { hilog } from '@kit.PerformanceAnalysisKit';
   import { fileGuard } from '@kit.EnterpriseDataGuardKit';
   ```

2. 初始化[FileGuard](https://developer.huawei.com/consumer/cn/doc/harmonyos-references/dataguard-fileguard#fileguard)对象guard，并且声明扫描结果回调函数。

   * 按照文件类型扫描公共空间文件，查看打印结果。

     ```typescript
     const TAG: string = 'FileGuard_Scan';
     const DOMAIN: number = 0x0000;

     /**
      * 启动公共目录文件扫描任务
      */
     function startFileScanTaskUnderCommonDir() {
       let guard: fileGuard.FileGuard = new fileGuard.FileGuard();
       let onReceiveFileList: (files: string[]) => void = (files: Array<string>) => {
         files.forEach((value: string) => {
           hilog.info(DOMAIN, TAG, `Succeeded in getting file: ${value}.`);
         })
       };
       let onCompleteScanTask: (count: number) => void = (count: number) => {
         hilog.info(DOMAIN, TAG, `Succeeded in getting count: ${count}.`);
       };
       let scanFileCallback: fileGuard.ScanFileCallback = {
         onReceiveFileList: onReceiveFileList,
         onTaskCompleted: onCompleteScanTask
       };
       guard.startFileScanTask(fileGuard.CommonDirScanType.MEDIA_ONLY, scanFileCallback);
     }
     ```

   * 扫描公共空间指定路径下的文件，查看打印结果。

     ```typescript
     const TAG: string = 'FileGuard_Scan';
     const DOMAIN: number = 0x0000;

     // ...
     /**
      * 启动指定目录文件扫描任务
      */
     function startFileScanTaskUnderSpecifiedDir() {
       let guard: fileGuard.FileGuard = new fileGuard.FileGuard();
       let path: string = '/data/service/el2/test';
       let onReceiveFileList: (files: string[]) => void = (files: Array<string>) => {
         files.forEach((value: string) => {
           hilog.info(DOMAIN, TAG, `Succeeded in getting file: ${value}.`);
         })
       };
       let onCompleteScanTask: (count: number) => void = (count: number) => {
         hilog.info(DOMAIN, TAG, `Succeeded in getting count: ${count}.`);
       };
       let scanFileCallback: fileGuard.ScanFileCallback = {
         onReceiveFileList: onReceiveFileList,
         onTaskCompleted: onCompleteScanTask
       };
       guard.startFileScanTask(path, scanFileCallback);
     }
     ```